Hydraulic pressure boosting device



June 2, 1964 c. L. ENGLISH HYDRAULIC PRESSURE BOOSTING DEVICE FiledApril 27, 1961 3 Sheets-Sheet 1 INVENTOR. CHAEL 55 A. NL/ZTH C. L.ENGLISH HYDRAULIC PRESSURE BOOSTING DEVICE June 2 1964 3 Shecs-Sheet 3Filed April 27, 1961 diw lrflfi. mwv HLn U T QL o& mm 9% QM HLHHIINVENTOR. cHAElE-S L. Emu/5H A TTDPA/FYS strokereversal and/or crankaction.

V r 3,135,210 HYDRAULIC PRESSURE BOOSTING DEVIC Charles L. English, 2204E. 25th Place, Tulsa, Okla.

Filed Apr. 27, 1961, Ser. No. 105,955

12 Claims. (Cl. 1ll349) invention relates to hydraulic powertransmission devices, and more particularly, but not by way oflimitation, to a device for boosting the pressure in a secondUnitedStates Patent Patented June 2, 196f1 from the pump end of thedevice without the occurrence of surges or pulsations. The curves ofoutput volume and pressure versus time for the pump are substantiallystraight lines-an advantage which cannot be claimed for existing duplex,triplex or even quintuplex pumps. Moreover, the cost of construction ofthe pump of this invention is considerably less than that of the lattertypes. For

. example, the heavy supporting bedframe which has charpower-drivenpumps employing cranks and flywheels,

have, for many years, accountedfor a large share of industrysmiscellaneous pumping needs. However, because of certain limitationsinherent in previous pump design,- versatility of application has alsobeen limited, so

' that any substantial variation in pumping requirements and conditionsnecessitates the employment of a different type of pump having pumpingcharacteristics suited to the particular needs at hand. Thus, althoughreciprocating pumps possess numerous characteristics which make theiruse attractive in many situations, other features preclude theirsuccessful use in other instances. One of the latter features is thepulsating discharge characteristic of such pumps, whether thereciprocating pump be directacting or power-driven. Such pulsations canbe reduced in magnitude by increasing the number of acting pistons orplungers and overlapping their strokes, as in duplex, triplex and othermultiplex pump systems, or by providing a surge chamber in which thepumped fluid is accumulated at peak delivery and discharged at strokereversal. However, neither of these devices for'reducing the magnitudeof the discharge pressure surges completely eliminate such pulsations,and the cost of the pumping unit is considerably increased when they areutilized.

The present invention contemplates a. rodless multiplex pump which ischaracterized by its adaptability to many specialized pumping needs, andby its ability to deliver a substantially constant volume of pumpedfluid at a high pressure without substantial output surge resulting fromThe method of stroke control used in the pump is unique in that eachstroke reversal is accomplished independently of the move ment of theengine pistons of the pump in their cylinders and is, instead, caused tooccur in alternate progressive relationship in each of the cylinderswhen the combined displacement of the pistons during their stroke issuch as to give any desired output of the fluid pumped within themechanical limits of the total engine cylinder volume available. IStroke reversal, then, occurs following a predetermined time intervaland after a predetermined volume of power fluid has been received in theengine pistons and is not brought about by an articulating means whichis common to all the engine pistons or to their rods and which isresponsive to the movement of one of the engine pistons to effect thereversal of the other engine pistons. The engine pistons of the rodlessbooster pump of the present invention function independently of eachother and without the managing influence of a common crank. Their onlyinterdependency resides in the requirement that the total volume ofpower fluid received in the engine cylinders for driving the enginepistons be the same for any given interval of time. Thus, as one of .theengine pistons decelerates toward the end of its stroke and prior toturn-around, the other engine pistons must at that time accelerate sothat an increased volume of power fluid may enter the other enginecylinders to offset the decrease in the volume of power fluid enteringthe first engine cylinacterized many previous multiplex pumps iseliminated. In order to permit the rodless booster pump of the presentinvention to function in the manner described, two salient features ofthe invention are essential. First, it is necessary that means beprovided to allow the acceleration of the engine pistons which are notapproach ing stroke end to anticipate the deceleration of the enginepiston which is undergoing stroke reversal. To this end- I providedash-pots which. function to decrease the de-' celeration of the enginepistons as they approach the lim its of their stroke, but which do notretard the accelera tion of the pistons as they move away from the endsof their stroke. This cushioning effect of the dash-pots is supplementedby a similar cushioning effect of power fluid transfer valves(subsequently to be described). which are utilized to periodically shiftthe impress of power fluid to opposite ends of the engine pistons; Thus,the cutback in the volume requirement of power fluid in one enginecylinder at the time of stroke reversal will not be so sudden that theengine pistons in the other engine cylinders will be unable toaccelerate fast enough to accommodate an increased volume of power fluidequal to the loss of requirement in the first cylinder.

Second, for the purpose of supplying an unvarying total volume of powerfluid to the engine cylinders, a source of a constant volume of powerfluid, such as a rotary pump, is utilized, and its discharge is dividedwith aportion of its output being directed to each of the enginecylinders. A main reversing or transfer valve is associated with each ofthe engine cylinders and functions to alternately transfer the powerfluid to opposite ends of its respective engine cylinder while receivingspent" power fluid from the low pressure end of the engine cylinder andreturning it to a power fluid sump or reservoir for recycling. Thereversal of the strokes of the enginepistons is thus effected by thethrowing of these transfer valves. The slight pressure loss which occursin the power fluid upon the throwing of the transfer valves tends tosupplement the cushioning or decelerating effect which is at that timeeffected by the dash-pot operative with respect to the engine pistonwhich is associated with the particular transfer valve being thrown.Also, a slight pressureincrease occurs in the portion of the power fiuidwhich is acting upon the other engine pistons whose strokes are notbeing reversed at that time.

. In order to permit the transfer valves to be thrown eriodicallyaccording to a predetermined optimum time sequence, a pilot valve isprovided which functions to i it permits the power fluid to accommodateeach engine This type of pilot valve managepiston individually accordingto its ability to travel, and thus compensates for inherent differencesin the resistance offered by each of the pistons to the impress of thepower fluid upon the working area of the piston. So far as I am aware,all other multiplex pumps supply a driving force to the pistons which issuflicient to drive each of them to the limit of the travel which isallowed by the length of the cylinders in which they move. Since,practicallyspeaking, the pistons will always be different from eachother in their resistance to movement in their respective cylinders,some power loss'results from the supplying of a greater volume of powerfluid to the lighter pistons (the ones olfering less resistance to themoving force of the power fluid) than is actually required to drive thepistons to the limit of their stroke. In other words, in a situationwhere dash-pots are utilized to retard the dc celeration of the pistons,an excessive energy loss occurs when the lighter pistons are driven moredeeply into their dash-pots in order to prevent the heavy piston fromshort-stroking.

- The principles of the invention may be applied with equal significanceto triplex, quintuplex or multi-cylinder systems, it being onlynecessary. (a) to make each of the engine pistons a free piston in thesense that no crank- In its broadest aspect, then, the present inventionmay be said to comprise a plurality of fluid pressure operated 1 enginepistons each having opposed engine piston areas for alternatelyreceiving the impress of a power fluid; pump means connected to theengine piston and responsiveto the movement thereof to pump a fluid;cylinders enclosing each of said pistons; means for decelerating saidengine pistons when the engine pistons approach the ends of saidcylinders; means for delivering a substantially constant volume of powerfluid, and valve means for directing the total volume of power fluidsupplied by said delivering means to all of said engine piston cylindersas the individual demands of each piston permit, the latter functionbeing made possible by the utilization, as a part of said valve means,of means for reversing the stroke of the engine pistons periodicallyaccording to what period of reversal is' determined to give the greatestoutput ca-' pacity with the least fluctuation or pulsation in the outputvolume and pressure over an extended periodof operation. Stateddifferently, the invention contemplates a multi-cylinder arrangement ofdirectly driven engine-topump piston units wherein the r'eversing valvefor each piston unit is controlled by a separate, individual pilotvalve, which pilot valves are thrown in a predetermined sequence so asto prorate the total absorbed motive fluid to each unit according to itsability to travel in its cylinder.

In a more specific aspect, the invention contemplates the securement ofa pair of pump pistons to each of the engine pistons, which pump pistonsare each enclosed in acylinder and are double-acting. This arrangementmay be adapted to the pumping of corrosive or gritty fluids, to highcapacity needs, or to high output pressure requirements. In everyinstance, the nonpulsating, steady output characteristic is maintained,and the initial manufacturing cost as well as the maintenance cost ofthe pump compares very favorably with other pumps which might bcharacterized by an output which is substantially free of pulsation andsurge.

An additional object of the present invention is to provide a rodless,multiplex hydraulic pump which is less expensive to manufacture andmaintain than other multiplex pumps of the same capacity and pressurecharacteristics.

A furtherobject of the present invention is to provide a rodless,multiplex hydraulic pump which permits all engine pistons of the pump totravel the maximum distance in their cylinders which they are capable oftraveling when subjected to a given volume of power fluid, thuseliminating power losses resulting from interruption of piston stroke bythe ends of the cylinders in which they move.

Another object of this invention is to provide a rodless, multiplexhydraulic pump which can absorb an extremely high horsepower input.

Another object of this invention is to provide a rodless,

multiplex hydraulic pump which is adaptable to many specialized pumpingrequirements.

. Another object of this invention is to provide a rodless, multiplexhydraulic pump, the capacity of which may be. rapidly. and easilyaltered during the operation of the pump.

Other objects and advantages will be apparent from the followingdescription when considered in conjunction with the accompanyingdrawings, wherein several embodiments of the invention are illustrated.

In the drawings:

vFIGURE 1 is a schematic view of a rodless, duplex hydraulic pumpconstructed according to the present invention.

FIGURE 2 is a side view in elevation of the arrangement of the pilotvalve in a preferred embodiment of the present invention. A portion of.the pilot valve is shown in section.

FIGURE 3A is an enlarged view in section of one of the main transfervalves. V

- FIGURE 3B is an enlarged view in section of the pilot valveshown inFIGS. 1 and 2.

FIGURES 4A, 4B and 4C are schematic views illustrating modifiedembodiments of the engine and pump cylinders of the present invention.

Referring now to the drawings in detail, and particularly to FIG; 1,reference characters 10 and 11 designate a pair of engine pistonsenclosed in engine piston cylinders Band 13, respectively, 'and eachhaving opposed faces 14 for alternately receiving the impress of powerfluid during the operation of the invention. A piston rod 16 extendsfrom each side of each of the pistons 10 and 11 in a direction normal tothe faces 14 of each piston and pass through openings 18 at each end ofthe engine cyl-' inders 12 and 1 3. A reduced diameter pump cylinder 20is secured to or formed on each end of each engine cylinder l2 and i3and communicates with the'respective engine cylinder through therespective opening 18. Pump pistons 22 are located inwardly from theends of the rods 16 so that an end portion 24 of each of the piston rods16 extends for a substantial distance beyond the pump pistons 22.

According to a construction well understood in the art, the relativedimensions of the engine cylinders 12 and 13, pump cylinders 20 andpiston rods 16 are such that the pump pistons 22 will move the length oftheir respective pump cylinders 20 as the engine pistons 10 and Ill aremoving the length of the engine cylinders 12' and 13. Adjacent that endof the pump cylinders 20 which is most remotely located with respect tothe engine cylinder 12 or 13 to which the pump cylinders are attached,the diameters of the pump cylinders are reduced to provide dash-pots26.' The inside diameters of the dash-pots 26 are slightly larger thanthe diameters of the end portions 24 of the piston rods 16 so that asmall clearance exists between the walls of the dash-pot 26 sure of thebooster pump increases.

and the piston rods 16 as the latter move into their respectivedash-pots.

In order to permit the dash-pots 26 to function in retarding themovement of the pump pistons 22 toward the end of the pump cylinders 20without impairing movement of the pump pistons away from the ends of thepump cylinders in which the dash-pots are located, a check valve 28 isprovided in the outer end of each of the dash-pots and is adapted toprevent the egress of pumped fluid from the respective pump piston byway of its dashpot, while permitting fluid to enter the pump cylinderfrom an intake conduit 30 by way of the dashpot. The intake conduits 30directing fluid to each of the several dash-pots 26 merge in a commonintake passageway 32 communicating at its intake end (not shown) withthe fluid which is to be pumped by means of the invention.

To facilitate the discharge of the pumped fluid from the pump cylinders20, a discharge conduit 34 communicates with each of the pump cylinders20 at a point inwardly of the respective dash-pot 26 located in the endof the pump cylinder. Each of the discharge conduits 34 is provided witha check valve 36 adjacent its point of connection to its respective pumpcylinder 20 so that loss of suction is prevented during the suction orintake stroke of the pump pistons 22. The discharge conduits 34 leadingfrom the several pump cylinders merge in a common discharge line 37which leads to the point of application of the pumped fluid.

For the purpose of supplying power fluid to the engine cylinders in themanner essential to the novel operation of the present invention,several major components are necessary and may be designated genericallyas a source of power fluid 38 capable of delivering a constant volume ofpower fluid, a pair of main transfer valves 40 and 41 associated withthe power cylinders 12 and 13, respectively, and some type of timingmechanism, such as the pilot valve means 42 shown in FIGS. 1, 2 and 3B,functioning to periodically throw the main transfer valves 40 and 41 ina manner hereinafter to be more fully described.

In a preferred embodiment of the invention illustrated schematically inFIGS. 1 and 2, the source of power fluid 38 comprises a centrifugal orrotary pump 44 connected to an intake line 46 and to a discharge line48. When a centrifugal pump is utilized, the pumps inherent slippagewill cause a rapidly increasing fall-01f of the pumps volumetricdisplacement as the discharge pres- It is therefore necessary to providea suitable metering device 50 (FIG. 1) in the hydraulic circuit of thepump, such as in the power fluid discharge line 48, which functions toconstantly monitor the volumetric flow through the line and to controlthe period of throw of the pilot valves (subsequently to be described)as may be required to maintain the displacement characteristics of thebooster pump. The discharge conduit 48 from the pump 44 branches into apair of conduits 52, each leading to one of the main transfer valves 40and 41.

Although a number of types of valves may be suitably used as the maintransfer valves 40 and 41 of the pres ent invention, I prefer to employtwo pairs of three-way piston valves 54 arranged with respect to eachother in the manner illustrated in FIG. 1. As shown in FIG. 3A, each ofthe three-way valves 54 includes a motor cylinder 56 containing a motorpiston 58. The motor piston 58 is connected through a valve stem 59 to atwo-faced poppet valve head 60. The valve head 60 is located in a valvechamber 62 which is substantially smaller diametrically than the motorcylinder. The valve head 60 during operation of the three-way valves 54alternately seats upon one or the other of the tapered seats 63 locatedat each end of the valve chamber 62. The housing portage of each set ofthree-way valves is arranged so that each three-way valve of each mainvalve 40 and the action of the shaft 78.

6 41 may receive power fluid from the conduits 52 and may dischargespent power fluid through conduits 64.

A pair of pilot valve passageways 68 communicates. with each pair of thecylinders 56 containing the large diameter motor pistons 58 of thethree-way valves, and each pair of the passageways 68 join in a commonconduit 70 which leads to the pilot valve means 42. There are thus twoconduits 70 leading to the pilot valve means 42-one from each of themain transfer valves 40 and 41. The return flow lines 64 leading fromeach of the main transfer valves 40 and 41 merge in a common flow returnline 46 which carries the spent power fluid discharged from the enginecylinders 12 and 13 back to the pump 44 for recycling. In actualoperation, it will be necessary or desirable to provide a suitable powerfluid reservoir or storage tank 72, as illustrated in FIG. 2, forreceiving power fluid from the return flow line 46 and supplying thepower fluid as it is needed to the pump 44.

The arrangements of the two three-way valves 54 in the main transfervalves 40 and 41 are identical. The porting and manifolding of the maintransfer valves 40 and 41 should be large enough to prevent theoccurrence of large pressure losses at the anticipated speeds ofoperation. Also, in order for valve effect in the three-Way valves 54 tobe identical in both opening and closing, the effective area of theengine piston 58 should be twice the effective area of the valve head60. Finally, the throw of the three-way valves 54 should be ofsufficient length that no obstruction of the valve portage areas isoffered.

The pilot valve means 42 which is utilized to eflect the reversal, orthrow, of the main transfer valves 40 and 41 is illustrated most clearlyin FIGS. 2 and 3B. In the preferred embodiment illustrated in thesefigures, the pilot valve means 42 comprises a pair of three-way valves74 and 76 which are set to be thrown at a phase difference of ninetydegrees from each other. To accomplish the desired difference in thetime of throw of the two valves 74 and 76, each of the pilot valves isoffset ninety degrees from the other upon a common shaft 78. The shaft78 is secured to the periphery of a face plate 80 which is coaxiallysecured to a shaft 82 driven through a variable speed reducer 84 by thesame motor 86 which is utilized to drive the power fluid pump 44. Eachof the three-way valves 74 and 76 is connected to receive power fluidfrom conduit 48 via the conduits 88 and 90, respectively, and toalternately discharge high pressure power fluid to, or receive spent,exhausting power fluid from, the main transfer valves 40 and 41 via theconduits 70. The two three-way valves 74 and 76 share a common dischargeport 92 through which the spent power fluid contained in the motorcylinder 56 can be released as the pilot valve means 42 is thrown in themanner hereinafter described. The discharge port 92 communicates with aconduit 94 which joins the return flow line 46, preferably upstream ofthe reservoir 72, or, optionally, the pump 44, as shown in FIGS. 1 and2.

The details of construction of the pilot valve means 42 are bestillustrated in FIG. 3B. Each of the three-way valves 74 and 76 of thepilot valve means 42 is provided with a high pressure intake port 106and a common port 108. A valve seat 110 is provided between the port 106and the port 108 of each of the three-way valves 74 and 76, and a ballvalve 112 is seated on a hollow shank 114 so that each valve 112 mayseat upon its respective seat 110 when its shank 114 is reciprocateddownwardly by It will be noted that the seats 110 are each provided witha bore 116 therethrough which is of larger diameter than the shank 114which passes therethrough. Thus, when the ball valves 112 are seated onthe seats 110 by the movement of the upper ends of the shanks 114 belowthe upper surface of the seats 110, the hollow interior of the shanks114 will be in communication with ports 108. Each of the shanks 114 hasan opening (not seen) at its inner end 117 which places the lower end ofthe shank in communication with a crankcase 118 which is common to thetwo three-way valves 74 and 76. As has previously been explained, spentpower fluid is discharged from the common crankcase 118 through adischarge port 92. it will be apparent that the inner end 117 of eachshank 114 may be secured to the shaft 78 by a rectangular yoke 119 toconvert the rotary motion of the shaft 78 to reciprocating motion of theshanks 114.

Operation As has been previously explained, the pump 44 delivers aconstant volume of power fluid to the conduit 48. To achieve constantvolume operation using a centrifugal pump, it is necessary to provide ametering device 5% (FIG. 1) which will sense fluctuations of the volumeof power fluid flowing in conduit 48 and control the pilot valve means42 to compensate for variations in the pump requirements. A constantdisplacement pump, such as a rotary pump, can, of course, be usedwithout being affected by changes in head and thus there is no need forsuch a volume metering device.

The power fluid supplied by conduit 48 is divided and flows throughconduit 52 to each of the main transfer valves 40 and 41.Simultaneously, a small portion of the power fluid in conduit 48 isdirected through conduits 88 and 90 to the three-way valves 74 and 76 ofthe pilot valve means 42. In the position of the pilot valve means 42and main valves 40 and 41 shown in FIG. 1, both of the three-way valves74 and 76 of the pilot valve means 42 are open to high pressure powerfluid due to the position of the eccentric shaft 7%, although the valve74 is just on the verge of closing following its open periodcorresponding to 180 degrees of rotation of the eccentric shaft 78.Threeway valve '76 has been open to high pressure power fluid fromconduit dtl during 90 degrees of the rotation of the eccentric shaft '78and will remain open for an additional 90 degrees of the shaftsrotation. In other words, each three-way valve 74 and 76 of the pilotvalve means 42 is open during one half the period of one revolution ofthe eccentric shaft 78 and is closed for one half of such period, withthe throws of the two valves 74 and 76 being 90 degrees out of phasewith each other or differing in time by one fourth the time required forthe shaft 73 to make one revolution.

With the throw of the pilot valve 42 occurring in this manner, it willbe apparent that power fluid will be directed via line 88 throughthree-way valve 74 and conduit 70 to the main transfer valve 4% duringone half theperiod of revolution of the eccentric shaft 78, and,therefore, of shaft 82, which'is connected through the variable speedreducer 84 to the motor 36. The same is true of power fluid that isdirected from conduit 90,

through three-way valve 76 and conduit 7% to the main transfer valve 41.It will further be apparent that power fluid so directed to the maintransfer valves 4% and 41 from the pilot valve 42 will act on the largediameter motor pistons 58 in the main transfer valves 48 and 41 to throwthe valves to the positions shown in FIG. 1. The concurrent supply ofpower fluid from the pilot valve means 42 to both main transfer valves4% and 41, will take place during 90 degrees or one fourth of therotation of the eccentric shaft 78, after which one of the valves 40 or41 will be thrown to the opposite posi tion due to the closure of itsrespective three-way valve 74 or 76, in pilot valve means 42, thusdenying access of high pressure power fluid to the large diameter motorpiston 58 of the main transfer valve so thrown. The concurrent closureof both of the three-way valves 74 and 76 in pilot valve means 42 willlikewise occur during 90 degrees of the rotation of the eccentric shaft73 so that during this phase of the shaft rotation, both the maintransfer valves 40 and 431 will be thrown to the opposite position fromtheir positions illustrated in FIG. 1.

The pattern of actuation of the main valves 40 and 3 41 in'response tothe pilotvalve means 42 may thus be summarized as follows:

(a) Both of the main valves 49 and 41 are concurrently positioned asshown in FIG. 1 for the period of time which it takes eccentric shaft 78to make one-fourth revolution;

(12) One of the main transfer valves 4th or 41 will then be thrown, dueto the closure of its respective three-way valve 74 or 76, and itspistons 58 and 60 will occupy the opposite position from that shown inFIG. 1. This relationship of the two main transfer valves 44B and 41will continue for the period of time required for the eccentric shaft 78to complete another quarter revolution;

(0) The other main transfer valve 49 or 41 will then be thrown due tothe closure of its respective three-way valve 74 or 76, so that bothmain transfer valves will occupy the opposite position from that shownin PEG. 1. Both main transfer valves will remain in this position duringthe period of time required for the eccentric shaft to rotate degrees;

(d) During the last 90 degrees of rotation of the eccentric shaft 73,one of the three-way valves '74 and 76 will be reopened, and itsrespective main transfer valve 49 or 41. will be returned to theposition shown in HS. 1.

It will be apparent, of course, that when the three-way valves 74 and 76of pilot valve means 42 are closed, the pistons of the three-way valves54. of the respective main valves 40 and 41 are reciprocated under theinfluence of power fluid from the conduits 52, and that exhausted or lowpressure power fluid in the valve motor cylinders is returned to thepilot valve means 42 by way of the respective conduit 74). Thisexhausted power fluid returns ultimately to the pump 44 by way of thehollow shank 114, crankcase 118, port 92 and the conduit 94.

For each of the phases of the main transfer valve operating cycle thathas been described'above, a corresponding condition characterizesthemovement of the engine pistons 16 and 11. Thus, with the maintransfer valves 40 and 41 occupying the positions shown in FIG. 1 andcorresponding to phase (a) of their operating cycle as described above,both engine pistons 10 and 11 travel in the same direction (asillustrated in FIG. 1). If both the main transfer valves 46 and 41 werethrown to the opposite position as described in phase (0) above, theengine pistons ill and 11 would both travel in the opposite direction,that is, toward the bottom of the page as they are viewed in FIG. 1.When only one of the main transfer valves 40 and 41 is reversed from theposition shown in FIG. 1, the engine pistons 10 and 11 travel inopposite directions from each other.

As will be apparent from FIG. 1, the end portion 24 of one of the pistonrods 16 of engine piston 10 is just entering its dash-pot 26, and thedirection of engine piston travel will soon be reversed due to closureof three-way valve 74 of pilot valve means 42. On the other hand, enginepiston 11 still has about one half its maximum possible stroke to travelbefore the end portion 24 of its piston rod 16 enters its respectivedashpot 26. The closure of the three-way valve 74 will cause thedirection of travel of engine piston 10 to be reversed, but will notchange the direction of travel of engine piston 11. From what haspreviously been said, it will be recalled that the throw of three-Wayvalves '74 and '76 of pilot valve means 42 is accomplished after fixedtime intervals (and/or power fluid volume intervals) which depend onlyupon the rotation of the eccentric shaft 73 whose rotation depends, inturn, upon the speed of motor 36 and the reduction ratio of variablespeed reducer 84. It will therefore be apparent that the stroke reversalof each of the engine pistons 19 and 11 is accomplished after a fixedtime interval and without regard to the position of the engine piston inits respective cylinder. It is thus possible to adjust the engine pistonstroking characteristics; both as to speed of travel and distance, byvarying the speed of rotation of eccentric shaft 78 through adjustmentof the variable speed reducer 84.

When the operation of the pump is commenced, the variable speed reducer84 will be set for a relatively small reduction in speed from the motor86 to eccentric shaft 78. This will cause rapid stroke reversal of theengine pistons and 11 so that they will travel only a portion of thetotal length of their respective engine cylinders before being reversed.The Weights of the two engine pistons 10 and 11 will differ slightly, aswill the frictional resistance of each to movement in'its respectivecylinder and other factors affecting the resistance which each offers tothe impress of the power fluid tending to move the pistons. In otherwords, one of'the engine pistons 10 and 11 may be termed lighter and theother heavier, if theseterms are used to describe the relative ease withwhich each may move in its cylinder. The lighter piston will, of course,be caused to travel farther during the time interval between reversalsthan will the heavier piston-that is, its stroke will be longer. Thus,at a given setting of the variable speed reducer 84, the lighter pistonmay travel eighty percent of its possible total travel, Whereas theheavier piston may travel only forty-five percent of its possibletravel. It is therefore apparent that due to the influence of thedash-pots 26 in smoothing out the stroke reversals, each piston willbase its stroke at, or into, at least one of the dash-pots 26.

After starting the pump with a low speed reduction ratio as describedabove, the frequency of stroke reversal is gradually decreased bygradually increasing the speed reduction between motor 86 and shaft 82.The volumetric input of power fluid from the pump 44 is maintainedconstant. A decrease in the frequency of stroke reversal causes thelength of the engine piston strokes to be increased until the stroke ofthe light piston is terminating at each of its ends with the endportions 24 of its shafts 16 in the dash-pots 26 at the ends of the pumpcylinders 20. On the other hand, only one of the end portions 24 of thepiston rods 16 attached to the heavy engine piston will enter one of thedash-pots 26 unless the frequency or stroke reversal is decreasedexcessively. In the'latter event, all of the dash-pots 26 may be enteredby the respective piston rod end portions 24a result which isundesirable in practically every instance, since power is wasted indriving the light piston rods 16 forceably against the bottoms of thedash-pots 26, or at least very deeply into the dash-pots.

With the stroke reversal frequency established so that each enginepiston is traveling its optimum stroke length in accordance with bothits and the other pistons indi= vidual ability to travel, and not aslimited by the length of its engine cylinder, the dash-pots willfunction to control the movement of the engine pistons so that the ends24 of the piston rods 16 will not bang against the ends of the pumpcylinders 29, and so that the movement of one engine piston will bedecelerated slowly enough at stroke reversal to allow the other enginepiston to accelerate a corresponding amount. Having, in the mannerdescribed, established the speed reduction ratio between motor 86 andshaft 82 which gives optimum stroking action by the engine pistons 10and 11 for a given volumetric input of the pump 44, the speed of themotor 86 may be increased or decreased to provide a larger or smallervolumetric input of power fluid from pump 44. This intentional variationin volume of power fluid pumped through conduit 48 from the pump 44 willbe I reflected in a proportionate increase or decrease in the totalamount of pumped fluid which is pumped by the pump pistons 22 so thatthe capacity of the rodless multiplex pump of the invention may beeasily increased or decreased. Moreover, at all capacities of the pump,the

orifice, is, as a practical matter, free of fluctuations in 10 volumeand pressure. In other words, a nonpulsating discharge is achieved. 1

In situations where the pressure demand upon the booster pump will varybetween a known maximum and minimum, the pilot valve cadence or periodof throw may. be set to give an engine piston stroke which will answeran average pressure demand between such maximum and minimum values. Thatis, less energy will be wasted in dash-pot entry than is Wasted when thepressure demand falls off to allow longer strokes, and more energy iswasted in dash-pot entry than is wasted when the pressure demand buildsup to cause shorter stroking. In this way, a modest margin of safety inthe extent of engine piston travel is established at an average pressuredemand so that the booster pump can tolerate the slight over-travel ofthe pistons which will be produced by a low pressure surge in outputdemand.

Although the present invention has been described by referring to adrawing illustrating a preferred embodiment of the invention in whichonly two engine pistons are utilized, the principles of the inventionare not confined to such an arrangement, and a rodless triplex orquintuplex pump may be constructed in accordance with the principles ofthe invention. It is only necessary to provide a main transfer valve foreach of the engine pistons which is utilized, and to modify the pilotvalve means in a manner which will permit it to throw the main transfervalves in proper sequence after fixed time intervals. However, due tothe nonpulsating output characteristics of the rodless duplex pumpdescribed above, and its high capacity potential, the duplex embodimentwill, in most adaptations, be equivalent to a crank-actuated triplexpumpof the prior art. The need for a triplex or quintuplex rodless hydraulicpump constructed according to the present invention will probably notoften arise, except perhaps in instances Where extreme dischargepressures of sizable volumes are demanded.

The duplex, double-acting embodiment of the rodless pump of thisinvention is quite adaptable to a variety of pumping requirements, andseveral adaptations of the pump are suggested by the modifications ofthe engine piston and associated pump pistions illustrated in FIGS; 4A,4B and 4C.

In FIG. 4A, each of the pump pistons 22 is single-acting. Pumped fluidis introduced to the pump cylinders 20 from the intake conduits viacheck valves 122 and dash-pots 26. The pump cylinders 20, contrary tothe arrangement illustrated in FIG. 1, are segregated from the enginecylinder and suitable packing 124 is provided around the piston rods'16. Each of the pump pistons 22 has a passageway 126 extendingtherethrough to permit pumped fluid to pass from one 'side of the pistonto the other upon actuation of a check valve 128 located in each pumppiston. Fluid is discharged from the pump cylinders 20 by way ofconduits 130. t

The arrangement depicted in FIG. 4B makes each of the piston pumps 22double-acting with pumped fluid being introduced viathe conduits 132 anddischarged via the conduits 134. Suitable check valves are provided inthe intake and discharge conduits 132 and 134, respectively.

The pump" illustrated in FIG. 4C utilizes a closed system containing acaptive hydraulic fluid; Thus, a single conduit 138 connects theouter'end of each of the pump cylinders 20. Pumped fluid is introducedto each pump cylinder 20 from an intake conduit 140 and is dischargedfrom the cylinders through conduits 142.

I As a basis for comparing the characteristics attributable to thedifferent pump end designs, let it be assumed that in each instance, 4A,4B and 4C, the inside diameter of the engine cylinder is five inches,the outside diameter of the piston rod is one and one-fourth inches, theinside diameter of the pump cylinder is-two inches, and the strokelength is forty-two inches. With these assumed uniform dimensions, thecharacteristics of the three pump types 1 i illustrated in FIGS. 4A, 4Band 40 may be tabulated as follows:

Pump 4A 4B 4C Pressure, Horsepower 115 115 115 Engine HorsepowerRequired to Produce 1,000 p.s.i. Output Pressure at One Stroke PerMinute 1.332 2.137 .812

From the tabulated data, it will be seen that in making each of the twopump pistons double-acting, as shown in FIG. 43, a very substantialincrease in volumetric capacity is achieved. On the other hand, muchhigher output pressure is achieved with the single-acting pump pistonar- 'rangement shown in FIG. 40 than with either the FIG. 4A or FIG. 43types. The FIG. 4A pump end arrangement is, in effect, a compromisebetween the FIG. 4B and 4C types insofar as volume and pressure outputsare concerned, but is moreeconornical to construct than the latterpumps.

From the foregoing description, it will be perceived that the presentinvention presents a novel rodless, hydraulic reciprocating pump whichis capable of adaptation to a variety of pumping needs and which inevery application delivers a substantially constant, nonpulsatingoutput. The pump is capable of absorbing extremely high inputhorsepower, and the power wasted in moving the engine pistons in theircylinders is reduced to aminimumby virtue of the ability of themechanism to supply power fluid to the engine pistons only as theirability to travel in their pistons may require.

Changes in the details of construction of the pump of the presentinvention will occur to those skilled in the art, and, insofar as suchchanges employ only the use of equivalent elements and structures and donot depart from the principles of the invention, they are deemed to fallwithin the scope of the invention as defined by the following claims.

I claim: 7

1. A hydraulic pressurebooster comprising a plurality of fluid pressureoperated engine pistons each having opposed engine piston areas foralternately receiving the impress of power fluid during operation of thebooster; pumping means connected to each of said engine pistons andresponsive to the movement thereof to pump a fluid; cylinders enclosingeach of said engine pistons; decelerating means operative to deceleratethe movement of said engine pistons when said engine pistons'approachthe ends of said cylinders, and allowing free, unimpaired movement ofsaid pistons away from the ends of said cylinders; means for deliveringa substantially constant volume of power fluid; main valve meansinterconnected between the ends of said cylinders and said power fluiddelivering means, said main valve means being shiftable between a firstposition to transfer power fluid to one of the ends of said cylinders,and a second position to transfer power fluid to the opposite ends ofsaid cylinders; and timing means connected to said main valve means forshifting said main valve means periodically, independently of themovement of the engine pistons and after predetermined intervals of timewhereby said engine pistons may be reciprocated in their respectivecylinders with each stroke acting over a predetermined time intervalwhich is independent of the time required for said pistons to travel anyspecific distance.

2. A hydraulic pressure booster comprising a plurality of fluid pressureoperated engine pistons each having opposed engine piston areas foralternately receiving the impress of power fluid during operation of thebooster; pumping means connected to each of said engine pistons andresponsive to the movement thereof to pump a fluid;

cylinders enclosing each of said engine pistons; decelerating meansoperative to decelerate the movement of said engine pistons when saidengine pistons approach the ends ofsaid cylinders, and allowing free,unimpaired movement of said pistons away from the ends of saidcylinders; means for delivering a substantially constant volume of powerfluid; main valve means interconnected between the ends of saidcylinders and said power fluid delivering means, said main valve meansbeing shiftable between a first position to transfer power fluid to oneend of said cylinders, and a second position to transfer power fluid tothe opposite ends of said cylinders; and timing means responsive to thedelivery of a predetermined amount of power fluid by said power fiuidsupplying means to throw said pilot valves whereby the strokes of saidengine pistons may be reversed after an optimum total volume of powerfluid has been delivered to one end of each of said engine cylinders.

3. A hydraulic pressure booster comprising a plurality of fluid pressureoperated engine pistons each having opposed engine piston areas foralternately receiving the impress of power fluid during operation of thebooster; pumping means connected to each of said engine pistons andresponsive to the movement thereof to pump a fluid; cylinders enclosingeach of said engine pistons; dash-pots cooperating with each of saidpumping means to decelerate the movement of said engine pistons towardthe ends of their respective cylinders; valve means in each of saiddash-pots removing the vacuum in said dash-pots when said engine pistonsmove away from the ends of said cylinders to permit free, unimpairedmovement of said engine pistons away from the ends of said cylinders;means for delivering a substantially constant volume of power fluid;main valve means interconnected between the ends of said cylindersandsaid power fluid delivering means, said main valve means being shiftablebetween a first position to transfer power fluid to one of the ends ofsaid cylinders, and a second position to transfer power fluid to theopposite ends of said cylinders; and timing means connected to said mainvalve means for shifting said main valve means periodically,independently of the movement of the engine pistons and afterpredetermined intervals of time.

4. A hydraulic pressure booster as claimed in claim 1 wherein saiddecelerating means comprises a plurality of dash-pots to decelerate themovement of said pistons toward the ends of said cylinders; and valvemeans in each of said dash-pots removing the vacuum in said dash-potswhen said pistons move away from the ends of said cylinders.

5. A hydraulic pressure booster as claimed in claim 1 and furthercharacterized to include adjusting means for varying the period of saidtiming means while said booster is operating.

6. A hydraulic pressure booster as claimed in claim 1 wherein said powerfluid delivering means comprises a rotary pump and said timing meanscomprises a pilot valve having its period of throw synchronized with theperiod required for said rotary pump to deliver a predetermined volumeof power fluid.

7. A hydraulic pressure booster as claimed in claim 1 wherein said powerfluid delivering means comprises a centrifugal pump; and regulatingmeans connected to the discharge of said centrifugal pump for varyingthe period of said timing means to maintain the volume of power fluidsupplied by said centrifugal pump constant despite fluctuations in thehead of said power fluid downstream from said regulating means.

8. A hydraulic pressure booster as claimed in claim 1 wherein saidpumping means comprises a pair of pump pistons connected to oppositesides of said engine pistons and a cylinder enclosing each of said pumppistons.

9. A hydraulic pressure booster as claimed in claim 8 wherein saidcylinders enclosing said pump pistons are hydraulically segregated fromsaid engine piston cylinders, and further characterized to include anintake conduit and a discharge conduit communicating with each end ofeach of said pump piston cylinders; and valve means in said conduitsadapted to permit pumped fluid to enter said pump piston cylinders fromsaid intake conduits and to be discharged from said pump pistoncylinders into said discharge conduits upon reciprocation of said enginepistons.

10. A hydraulic pressure booster as claimed in claim 8 wherein saidcylinders enclosing said pump pistons are hydraulically segregated fromsaid engine piston cylinders, and further characterized to include afluid passageway interconnecting the remote ends of the two pump pistoncylinders adjacent each engine cylinder; a captive liquid enclosed insaid remote ends of said pump piston cylinders and said conduit; anintake conduit and a discharge conduit communicating with the end ofeach of said pump piston cylinders opposite said remote end and adjacentsaid engine piston cylinders; and valve means in said conduits adaptedto permit pumped fluid to enter said pump piston cylinders from saidintake conduits and to be discharged from said pump piston cylindersinto said discharge conduits upon reciprocation of said engine pistons.

11. A hydraulic pressure booster as claimed in claim 1 wherein there aretwo of said engine pistons, and said reversing valve means comprises afirst pair of three-way valves each having two of its portscommunicating with two of the ports of the other three-way valve in saidfirst pair; said first pair of three-Way valves being responsive to saidtiming means to direct a portion of the power fluid delivered by saidpower fluid delivering means to one end of one of said engine pistoncylinders, and, alternately, to the other end of said one engine pistoncylinder; and a second pair of three-way valves each having two of itsports communicating with two of the ports of the other three-way valvein said second pair; said second pair of three-way valves beingresponsive to said timing means to direct the remaining portion of thepower fluid delivered by power fluid delivering means to one end of theother of said engine piston cylinders, and, alternately, to the otherend of said other engine piston cylinder.

12. A hydraulic pressure booster comprising a pair of fluid pressureoperated engine pistons each having opposed engine piston areas foralternately receiving the impress of power fluid during operation of thebooster; an engine cylinder enclosing each of said engine pistons; apiston rod extending from each of'the opposed engine piston areas; apump piston carried by each of said piston rods and offset axiallyinward from the free ends of said rods; a pump cylinder enclosing eachof said pump pistons; a dash-pot at the end of each of said pumpcylinders most remotely located with respect to the nearest adjacentengine cylinder, said dash-pots each being of larger diameter than thefree end of the adjacent piston rod and smaller diameter than theadjacent pump piston; an intake conduit communicating with each of saiddash-pots at the bottom thereof; a check valve associated with each ofsaid dash-pots operative to permit fluid to enter said pump cylindersfrom said intake conduits via said dash-pots while preventing thedischarge of fluid from said pump cylinders into said intake conduits; adischarge conduit communicating with each of said pump cylinders; acheck valve associated with each of said discharge conduits forpreventing the ingress of fluid to said pump cylinders from saiddischarge conduits during theintake stroke of said pump pistons; meansfor supplying a substantially constant volume of power fluid to saidengine cylinders; fluid actuated transfer valves associated with each ofsaid engine cylinders for alternately directing power fluid from saidpower fluid delivering means to the opposite ends of each of said enginecylinders; a pilot valve hydraulically connected to each of said fluidactuated transfer valves and to said power fluid supplying means andadapted to throw said transfer valves when said pilot valves are thrown;and timing means responsive to the delivery of a predetermined amount ofpower fluid by said power fluid supplying means to throw said pilotvalves whereby the strokes of said engine pistons may be reversed afteran optimum total volume of power fluid has been delivered to one end ofeach of said engine cylinders.

References Cited in the file of this patent. UNITED STATES PATENTS2,145,854 Bijur Feb. 7, 1939 2,420,896 Meyers May 20, 1947 2,486,079Tucker Oct. 25, 1949 2,508,298 Saari May 16, 1950 2,819,835 Newhall Jan.14, 1958

1. A HYDRAULIC PRESSURE BOOSTER COMPRISING A PLURALITY OF FLUID PRESSUREOPERATED ENGINE PISTONS EACH HAVING OPPOSED ENGINE PISTON AREAS FORALTERNATELY RECEIVING THE IMPRESS OF POWER FLUID DURING OPERATION OF THEBOOSTER; PUMPING MEANS CONNECTED TO EACH OF SAID ENGINE PISTONS ANDRESPONSIVE TO THE MOVEMENT THEREOF TO PUMP A FLUID; CYLINDERS ENCLOSINGEACH OF SAID ENGINE PISTONS; DECELERATING MEANS OPERATIVE TO DECELERATETHE MOVEMENT OF SAID ENGINE PISTONS WHEN SAID ENGINE PISTONS APPROACHTHE ENDS OF SAID CYLINDERS, AND ALLOWING FREE, UNIMPAIRED MOVEMENT OFSAID PISTONS AWAY FROM THE ENDS OF SAID CYLINDERS; MEANS FOR DELIVERINGA SUBSTANTIALLY CONSTANT VOLUME OF POWER FLUID; MAIN VALVE MEANSINTERCONNECTED BETWEEN THE ENDS OF SAID CYLINDERS AND SAID POWER FLUIDDELIVERING MEANS, SAID MAIN VALVE MEANS BEING SHIFTABLE BETWEEN A FIRSTPOSITION TO TRANSFER POWER FLUID TO ONE OF THE ENDS OF SAID CYLINDERS,AND A SECOND POSITION TO TRANSFER POWER FLUID TO THE OPPOSITE ENDS OFSAID CYLINDERS; AND TIMING MEANS CONNECTED TO SAID MAIN VALVE MEANS FORSHIFTING SAID MAIN VALVE MEANS PERIODICALLY, INDEPENDENTLY OF THEMOVEMENT OF THE ENGINE PISTONS AND AFTER PREDETERMINED INTERVALS OF TIMEWHEREBY SAID ENGINE PISTONS MAY BE RECIPROCATED IN THEIR RESPECTIVECYLINDERS WITH EACH STROKE ACTING OVER A PREDETERMINED TIME INTERVALWHICH IS INDEPENDENT OF THE TIME REQUIRED FOR SAID PISTONS TO TRAVEL ANYSPECIFIC DISTANCE.